Some things to try, replace the gnutella.net file as described here If LW 4 Will Not Connect (click on the blue link). LW must be closed at that time. If the other LW is connecting fine, perhaps even try the gnutella.net file from that program's preference folder.

I presume you set LW's firewall option for port forwarding, the same port as you port forwarded the belkin. Manual port forward instructions & sample image

(yes there are some people who do not know what hyperlinks are. lol)